1. Field of the Invention
The invention is related to the field of flexible boots and in particular to flexible boots for sealing the open ends of constant velocity universal joints which compensate for both angular and linear displacement.
2. Description of the Prior Art
Constant velocity universal joints are currently being used in the drive trains of automotive vehicles. In such vehicles, one universal joint connects a propeller shaft to a rotary output of the vehicle's transmission while a second universal joint connects the propeller shaft to a wheel. As the vehicle travels over an uneven surface or leans to one side or the other during turns, the wheels move up and down in a plane approximately normal to the propeller shaft. Therefore, provisions are made in such universal joints to accommodate for the changes in the distance between the wheel and the transmission as the wheel moves up and down or the engine or transmission vibrates under high loads.
Constant velocity (CV) mechanical joints such as those disclosed by Hazebrook et al in U.S. Pat. No. 4,573,947 or by Kurzeja et al in U.S. Pat. No. 4,605,384 provide for both angular and linear displacement between the inner and outer joint members. Hazebrook et al shows a flexible boot having a linearly extending convolute to compensate for both angular and linear displacement of the inner and outer joint members. In contrast, Kurzeja et al teaches a flexible boot having a plurality of annular convolutes which diminish in diameter as the boot extends outwardly from the constant velocity universal joint. This type of boot is also taught by Ukai et al in U.S. Pat. No. 4,730,834 and 4,805,921, Hadick et al in U.S. Pat. No. 3,830,083, and Mizutani et al in U.S. Pat. No. 4,278,262 as well as various other patents. These patents teach a single set of convolutes of diminishing diameters which compensate for the angular as well as the linear displacement of the inner joint members relative to the outer joint members.
In an alternate configuration, Billet et al in U.S. Pat. No. 4,556,399 teaches a protective boot for a front wheel vehicle having a first section consisting of a plurality of annular convolutions of diminishing diameters and a single annular convolute spaced therefrom.
It has been found that such boots had to have relatively large diameters to prohibit the seal boot from being over stretched when there is a combination of an angular displacement and linear extension or overly compressed when there is an angular displacement and a linear contraction between the two joint members. The present invention is a flexible boot for a constant velocity universal joint which significantly reduces these problems.